Safety switch



W. A. WULLE SAFETY SWITCH July 11, 1933.

5 Sheets-Sheet 1 Filed Jan. 10, 1931 ll: T4.

INVENKOR. W 5 76 1%. 2 62676 V ATTORNEYS.

W. A. WULLE July; 11, 1933.

SAFETY SWITCH Filed Jan. .10, 1931 5 Sheets-Sheet 2 III/III! INVENTOR. Wi wam @fl. %ZZ6 ATTORNEY/5 July 11, 1933. w A. wULLE 1,917,567

SAFETY SWITCH Filed Jan. 10, 1931 5 Sheets-Sheet 3 ATTORNEYfI.

W. A. WULLE July 11, 1933.

SAFETY SWITCH Filed Jan. 10, 1931 5 Sheets-Sheet '4 I N V ENTOR. WQ'ZZzLQWZ o7. WZzZZe r) v j m @z, ATTORNEYQ 11, 11, 1933. w, A WULLE v 1,917,567

SAFETY SWITCH Filed Jan. 10, 1931 5 Sheets-Sheet 5 H a 11/ [H 1/ I :3

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ATTORNEYS.

Patented July 11, 1933 UNITED STATES PATENT OFFICE WILLIAM A. WULLE, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE PYLE-NATIONAL COMPANY; OF'CHICAGO, ILLINOIS, A CORPORATION OF NEW JERSEY SAFETY Application filed January 10, 1931. Serial No. 507,812. i

My invention relates'to improvements in safety electrical switches and has for one object to provide a combined switch and terminal plug with housing wherein the terminal plug cannot be inserted unless the switch is open and wherein the plug cannot be withdrawn when the switch is closed and further to provide a cover for the switch box which unless specially manipulated for the purpose I of adjustment and the like protects the switch and the switch operator by making it normally impossible to open the cover when the switch is closed and to close the switch when the coveris'open. Other objects of my inis vention will appear from time to time in the specification.

My invention is illustrated more or less diagrammatically in the accompanying drawings, 'wherein Figure 1 is a plan View showing the cover open with the switch for the purposes of illustration closed;

Figure 2 is a side elevation showing the cover closed 2-- Figure 3 is a longitudinal section Figure 4 is a. detailed fragmental longitudinal section showing'the switch in the closed position;

Figure 5 is a similar detail showing the IN switch in the open position;

Figure 6 is a fragmental section through the terminal plug socket and associated parts in the position assumed when the plug is not present;

5 Figure 7 is a similar view showing the plug in position the switch being open;

Figure 8 is a similar view with the plug itself in section. the switch being closed.

A is a switch box. It has a bottom A and if! side walls A integral therewith. Ears A are provided whereby the box may be mounted on any suitable support. Lugs A* support hinge pins A and lugs A on the cover A Locking lugs A support pivot pins A and thumb screw locking links A upon which are threaded thumb screws A to engage lugs A to seat the cover on the box. A 'is a spring hasp on the cover adapted to engage an eye A so that the box may to for additional security be padlocked in the closed position. The spring hasp A is loosely socketed in the pocket A being associated with a pivot pin A and an adjustable screw A which may be positioned to 5 control the tension'of the spring hasp.

mounted in the snap cam C B is an insulating switch panel mounted in the bottom of the box A. This switch panel carries fuses B in spring clips B B B are flexible spring fingers mounted on the switch block B each finger B being electrically connected to one of the spring clips B each finger B being in electric relation with a conductor B which passes out of the box through the gap B and conduit B B B are switch blades, each blade being pivoted at one end on the spring fingers B adapted to be forced between the spring fingers B by means of an insulating block B which carries the two blades B and a link pivoted on a yoke B on the block at one end and on the switch crank bar B at the other end.

The switch crank bar B is mounted at one end in the bearing sleeve C in the wall of the housing and at the other end is rigidly This snap cam has an ear C upon which is pivoted a socket carrying a spring pin or plunger 0*. The pin C slides in the trunnioned block C oscillatably mounted in a bracket C on the wall of the housing. C is a spring encircling the pin compressed between the sleeve C and the block C so that when the parts are in the position shown in Figure 4 with the switch closed the spring tends to keep the switch closed. hen the parts are in the position shown in Figure 5 with the switchopen the spring tends to keep the switch open, the two positions being at opposed sides of the center line of movement from open to closed position or vice versa.

D is the control lever. It has a handle D It is rotatably mounted in the wall of the switch box and its movement is limited by the lugs D D. The lug D is apertured as at D in register with an aperture D in the lug D on the handle so that the switch may be locked in the open position by padlock or the like. The crank arm B is rigidly mounted in the member C which member is rotatably mounted on the crank extension where it projects inwardly through the wall of the housing. D is a driving lug rigidly connected to the crank D and having a tooth D overlying the member C which member is reduced in diameter as at D", the reduced portion terminating in driving abutments D D so that the cam member C may have a limited movement with relation to the lever D. This arrangement permits one or other of the driving abutments D D to be engaged by the member D as the lever D is rotated to compress the spring C until the member C is in line with the pin G. Further movement permits the spring C to snap the cam member C ahead to give the characteristic sudden opening or closing of the switch.

Mounted for rotation with lever D is the locking cam E. This locking cam E has a cylindrical locking face E terminating in a release pocket E E is a lock lever pivoted on the inside of the housing and associated with a spring E tending to rotate that lever in a clockwise direction as shown in Figures 4 and 5. This lever has a cam engaging tail E which tail may engage the locking face E of the cam E when the switch lever is in the closed position or which when the switch lever is in the open position as shown F igure 5 drops into the pocket E to lock the switch lever or arm in the open position. The cover A has a pocket E in which the lever E may operate and this lever terminates in a latch hook E to overlie the latch pin E in the cover. In the position shown in Figure 4 then when the switch is closed, the latch is locked and the cover cannot be opened. In the position shown in Figure 5, the latch is open and the cover can be closed or opened. It will be noted that the cover is never in the position shown in Figure 5 without the latch being thrown into substantially the position shown in Figure 4. This is done by the lug E on the edge of the cover engaging the hook E which engagement results in causing the latch to move in counterclockwise direction into hooking engagement with the pin E to lock the cover and at the same time causing the latch tail E to move out of engagement with the pocket E and permit the cam E to rotate. For purposes of illustration in Figure 5, the cover is shown in place but it will be noted that the lug E is removed to permit the latch hook E to come up as the lock lever E is moved in clockwise direction about its pivot.

The above arrangement takes care of the situation where it is necessary to have the cover locked in place before the switch is closed. Of course, the operator may manipulate this latch by hand so as to free the cam E and permit the switch to be closed as may be done by the electrician when he is testing circuits but ordinarily this movement takes place and the switch can be closed only when the cover is down and after the cover down and the switch is closed, the cover cannot be opened by anyone without first opening the switch.

Pivoted to the cam member E is a connecting rod F which is caused to reciprocate by the rotation of the switch handle. This connecting rod F extends to the end of the housing where it terminates in a yoke F which is threaded onto the connecting rod and provided with a. lock nut F". This yoke F is provided with a longitudinal slot F engaging a pin F on one of the arms of the three arm lever F 5 which lever is pivoted on the pin F in the socket housing F As will hereinafter appear a connection is established between the hand operated switch and the terminal socket through the medium of this connecting rod whereby locking means are controlled to prevent the insertion of a plug in the terminal socket when the switch is closed and to prevent the withdraw- .al of the plug if a plug is there unless the switch is open. In other words, there is a combined safety interlock to make it impossible to insert or withdraw a terminal plug unless the circuit is open.

The socket housing F is attached to the end of the main housing or box A and contains an insulated terminal base G. Conductors Gr G lead from the fuses B B to spring terminal fingers G in the boss G which extend forwardly from this insulated socket G on one side thereof and eccentric to the same. G is a cover pivoted on the housing F adapted to close the opening in register with the base G and provided with a spring G to cause such closing when the plug is not present. The housing F 7 is generally circular adjacent the base G but has a relatively flat extension at one side as shown in Figure 2 to enclose the interlock mechanism. G is a terminal plug. It contains an insulating block Gr having a socket as indicated to enclose the projection G In this socket are two terminal blades G adapted to engage the spring terminal jaws G Since this socket and the member G are not circular and are disposed eccentrically to the plug and base, engagement can take place only when they are in line and the two members are held against angularmovement and compelled to be in a predetermined angular relation before they are engaged. Conductors Gr terminate in the spring fingers G to provide electric connection through the wires G fingers or jaws G fingers G, wires G to the two poles of the knife blade of the knife switch.

The terminal plug G is apertu red as at H. i

lock pin into engagement with the hole H in the switch plugGr and holding it in position to lock the plug in place. When the switch is opened theconnecting rod F is moved away from the lever F into the position shown in Figures 6 and 7 rotating the lever F in a counter clockwise direction, exerting a tension on the spring H and disengaging the latch pin and the plug. Under these circumstances the plug may be withdrawn. H is a yoke pivoted in the housing F It supports one end of the spring H the other end being supported by one of the arms of the three way lever A This yoke has an engagement pad or part I which extends down into the path of the terminal plug. When the plug is withdrawn, this yoke under the influence of the spring H is held in an inclined posi tion as shown in Figure 6. hen the plug is inserted it engages this pad and rotates the yoke in a clockwise direction as shown in Figure 7. This rotation can es the cam H on the yoke to move out of line with the end of the yoke F It will be noted that in Figure 6 the cam engaged by the yoke and the connecting rod F can not be moved forward, thus the switch is held against operation by this yoke and cam engagement until the plug has been inserted to disengage this look. Of course, the operator might reach in by lifting up the cover of the plug housing and push the yoke to one side with his linger or some instrument, if it were necessary to be able to operate the switch. But under ordinary circumstances this insures that the switch locked in the open position and cannot be closed until a plug has been inserted and after the plug has been inserted the switch may be operated but it closed locks the plug against withdrawal.

The wires G G are safety wires. G" extends from a binding post on the housing to a terminal socket just like the socket for the wire G The wire G connects to socke' in the plug just like the sockets tor the wires G When the plug is in, led a circuit is closed between the wires G G. The wire G is grounded as indicated. on the handle G. It also extends down through the conduit parallel with the wire 1 i and is grounded on the machine or apparatus controlled or furnished with power from the box, the idea being that this ground wire breaks both the switch boX, the plug handle and the machine or apparatus supplied with current by the ex tension cord in the event of short circuit. It sometimes happens that a motor mounted on a wheeled truck will have a short, in which case the operator standing on a steel floor touching the motor will get a shock. This safety wire protects allthe apparai'Lus against this and if there is a short, there will be a return circuit of lower resistance than the body of the operator and he will be safe.

I claim:

1. A switch mechanism including in con bination, a housing, a movable switch member in said housing, a cover for said housing, a crank for actuating said switch member, a cam disc immovably fastened to said crank, said. disc having a gap in its cam surface, a

tooth lying within said gap and movable within said gap relatively to said disc, an operating lever carrying said tooth for initiating movement of said disc, a spring connected to said disc for completing movement thereof with snap action, a rod pivoted to said disc and carrying said spring, a bearing for said rod with respect to which said rod. is movable, said rod, spring and disc constituting a toggle mechanism for moving said crank to actuate said switch after the initial movement thereof by said lever and cam disc.

2. A plug lock for a switch mechanism including in combination, a bell crank, a stud thereon, the switch mechanism having a plug receiving socket, a plug insertable in said socket, said plug and socket having registering apertures for receiving said stud, a movable switch member, means for moving said switch member to closed position, means operable by said last-n'ientioned means for actuating said bell crank to move said stud into said registering apertures of the socket and plug, a yoke having a part lying in the path of the plug and having an abutment normally positioned to prevent movement of said bell crank by said last mentioned means to engage said stud with the socket aperture in the absence of the plug, the application of the plug to sa id socket engaging said yoke part and moving said abutment out of abutting relation with respect to the bell crank, the normal position oi the yoke abutment with respect to the hell crank actuating means preventing the closing of the switch member when the plug absent.

3. A switch mechanism including in com bination, a housing, a plug receiving socket forming a part of said housing, a plug insertable in said socket, said socket and plug having registering apertures, a switch mechanism within said housing, a plug locking mechanism including a stud, means for actuating said switch mechanism, means operable by said last-mentioned means for actuating the plug locking mechanism to move the stud into said apertures when said switch mechanism is actuated to close the switch, a yoke having a part lying in the path of said plug and. having an abutment engageable against the plug locking mechanism for pre venting actuation of the switch mechanism and plug locking mechanism in the absence of the plug, the insertion of a plug in said socket engaging said voke part and moving said abutment away from the plug locking mechanism, actuation of the switch mechanism then being effective to close the switch and lock the plug by engagement of said stud with the registering apertures in the plug and socket.

4. A switch mechanism including in combination, a housing, a plug receiving socket as a part of said housing, a switch mechanism within said housing, means for actuating said switch mechanism, said socket having an opening therein, a bell crank disposed adjacent said socket and having a stud thereon for entering said opening, connections between said switch actuating mechanism and said bell crank for moving said stud into said opening when said switch actuating mechanism is moved in a direction to close the switch, and an abutment engageable against the bell crank actuating mechanism for preventing movement thereof in the absence of a plug, the abutment serving to prevent actuation of the switch closing mechanism when in abutting relation with respect to the bell crank actuating mechanism.

5. An electric switch apparatus including in combination, a housing, a throw switch within said housing, a socket carried by said housing, a plug insertable in said socket, a cover for said housing, means for operating said switch, means actuated by the closing of the cover for locking the cover in closed position, said last-mentioned means being maintained in locking engagement with the cover by engagement of said switch actuating means therewith, means for locking a plug in said socket, said locking means being operable by the switch actuating means, and an abutment for preventing actuation of the switch actuating means to move the switch in closed position and the plug locking means to locking position in the absence of a plu 6. In a device of the class described, in combination, a casing having switch mechanism therein, said switch mechanism including a member movable to open and close the switch, a plug socket on said casing having an aperture in its wall, a bell crank carrying a projection for entering said aperture under certain conditions, means for moving said movable switch member to closed position, connectiolls between said last-mentioned means and said bell crank for moving said projection into the socket aperture when said movable switch member is moved in a direction to close the switch, and a stop member having a part lying in the socket in the path of the plug and engaging said bell crank for preventing movement of it and the movable switch member to switch closing relation in the absence of a plug in said socket, the insertion of a plug in said socket engaging said stop member part and moving said stop member out oi stopping engagement with the bell rank and its connected parts.

7. A switch mechanism including a housi ng, a removable cover for said housing, said switch mechanism including a movable member tor closing and opening circuit relation through said switch mechanism, a socket carried by said housing, a plug insertable in said socket, means for actuating said movable switch member, a pawl pivoted inside said housing for hooking engagement with the cover, said pawl and. cover having cooperating parts for moving said pawl into hooking engagement with the cover as the cover is closed, means carried by the switch actuating means for maintaining said pawl and cover in hooked engagement as long as said movable switch member is in closed position, said socket and plug having registering apertures, a bell crank carrying a projection for cntcring said registering apertures, connections between said bell crank and said switch operating in ,cllim ism for moving said projection into the apertur in said socket and plug as said switch member is moved to closed position, a yoke having a part lying in the path of said plug, raid yoke being ellective to prevent closing of the switch mechanism in the absence oi a plug, the insertion of a plug en gaging said part to move said yoke out of position otherwise preventing actuation of thc switch closing mechanism.

8. A switch mechanism including a housin g, a removable cover for said housing, said switch mechanism including a movable member tor closing and opening circuit relation through said switch mechanism, a socket T31- ried by said housing, a plug insertable in said socket, means for actuating said movable switch member, a pawl. pivoted inside said housing for hooking engagement with the cover, said pawl and cover having cooperating parts for moving said pawl into hooking engagement with the cover as the cover is closed, means carried by the switch actuating means for imiintaining said pawl and cover in hooked engagement as long as said movable switch member in closed position, said socket and plug having registering apertures, a bell crank carrying a projection for entering said registering apertlu'es, connections between said bell crank and said switch operating mechanism for moving said projection into the apertures in said socket and plug as said switch member is moved to closed position, and a stop member having a part lying in the path of movement of the plug in its application to said. socket, said stop in the absence of a plug engaging the connections between the suit h actuating means and the bell crank for preventing movement of said parts to close said switch and lock the cover, said stop being moved "From engagen'ient with said parts by a plug when the latter inserted in said socket.

Signed at Chicago, county of Cook and State of Illinois, this 8th day of January XVILLIAM A. VULLE. 

